1. Field of the Invention
The present invention relates to an automatic grinding apparatus for grinding the end faces of a cylindrical-shaped iron core, a component part of an armature, simultaneously and efficiently.
2. Background of the Invention
An iron armature core 1 (or core 1) shown in FIG. 6, a part of a rotating armature of a motor, used in such pumping devices as fuel pump motor, comprises a plurality of thin steel strips (of 0.35-1.00 mm strip thickness) are laminated to a certain core thickness T and has a plurality of slots 2 formed on the peripheral surface thereof. The strip material is usually a silicon steel to provide special electrical characteristics.
The entire core 1 is coated with an insulating material, such as an epoxy resin, for electrical insulation, then windings are installed in the slots. An armature shaft 3 is press fitted into a shaft hole formed in the axis of the core 1.
In such a case, the end faces 1a, 1b of the core 1, made by laminating silicon steel strips, are covered with a silica film, whose thickness is of the order of several micrometers.
Because this silica film is poorly bonded to the base steel, an epoxy coating applied on top of such a film could easily peel off from the core 1 to expose the base steel, thus producing a defective core which could present shorting problems. For this reason, the practice is to manually remove such films from both end faces 1a, 1b of the silicon steel iron core 1.
However, such manual operation is inevitably time consuming and inefficient, and contributed to rising prices of armature components.
Therefore, there was a need for automated apparatus for removing the silica films from both end faces 1a, 1b of a core 1 efficiently and cost effectively.